If you've enabled iCloud Photo Library on your iPhone or iPad, you may have noticed that all of your videos aren't showing up. I first noticed this a few days ago while searching for a video I know I had taken on my iPhone a few days prior. For some reason, it wasn't showing up on my iPad, which also has iCloud Photo Library enabled. Digging deeper, some videos that I actually took on my iPhone were also missing. As it turns out, there's a switch you can flip across your devices in order to get videos syncing properly to and from iCloud Photo Library. And for the time being, it also seems to fix the missing videos bug too!
How to fix video syncing issues with iCloud Photo Library for iPhone and iPad
Launch the Settings app on your iPhone and iPad.
Tap on Videos.
Turn On the option for **Show All Videos"".
You'll notice that the text changes when you toggle this option on and off. If the Show All Videos option is turned on, all videos in iCloud Photo Library will be shown, regardless of what device they were taken on. If it's turned off, only the videos physically downloaded on a particular device will be shown in the Photos app. In my experience, turning this option on also seemed to bring back some missing videos that somehow got removed from my iPhone when uploading to iCloud Photo Library. This is most likely a bug in iCloud Photo Library. Luckily this trick solved it and brought my videos back from what I can tell.
Hopefully this is an issue Apple addresses but as always, remember iCloud Photo Library is still in beta. That being said, give this a try and see if it brings back your missing videos!